As is generally known, some automotive exhaust systems employ a flexible connection member or coupler disposed between two exhaust pipes in order to absorb undesirable vibrations input into the exhaust piping, absorb any thermal expansion or contraction of the exhaust piping, and compensate for any misalignments in the exhaust piping. These couplers are generally formed of an inner flexible metal bellows member and an outer braid cover surrounding the outer periphery of the bellows member. Exemplary of such a coupler is U.S. Pat. No. 5,769,463 to Thomas. The braid cover is normally in very close proximity to, if not in direct contact with, the bellows. Such a placement of the braid cover often leads to friction between the bellows and the braid cover thereby resulting in wearing and premature failure of the bellows and braid cover. In currently known embodiments where the braid cover is spaced at any significant distance from the bellows member, such as in U.S. Pat. No. 6,902,203 to Kang, the braid cover has to be supported by some rigid support means in order to maintain that spacing.
It is well known in the industry that one source of energy loss and inefficiency in internal combustion engines is the loss of heat through exhaust gases. Heat lost though the engine's exhaust gas results in a loss of energy that would otherwise be in the form of mechanical energy produced by the engine. Furthermore, keeping heat in the exhaust gases speeds the gases up in their travel though the exhaust system thereby reducing the amount of back pressure on the engine. Thus, it is desirable for internal combustion engines to have exhaust systems that lose as little heat as possible.
It is also known in the industry to construct the braid cover of many bundles of fine metal wires. The bundles are knitted alternatively to each other in a spiral direction. Normally, the spacing between the bundles and the density of the braid cover is not of importance other than to ensure that the braid cover generally protects the bellows from sand, gravel and other road debris. It is unknown in the prior art to form the braid cover in a manner wherein it creates a thermally insulating layer around the bellows.
Accordingly, a need exists for a braid cover that includes a self-supporting portion spaced at a distance from a bellows member in order to create a meaningful air gap therebetween. A need also exists for a method for manufacturing such a braid cover. A further need exists for a coupler that has increased insulating properties in order to maintain heat within the exhaust gas flowing through the coupler.